Users getting error adding phone numbers from Taiwan and Russia to MFA

Taiwan (+886), Russia (+7), and Uzbekistan (+998) are in the list of regions that require explicit opt‑in for Microsoft Entra MFA telephony (SMS/voice) verification. If the tenant is not enabled for telecom authentication in these regions, users will see generic errors when trying to add or verify phone numbers from those countries.

To resolve:

1. Confirm the affected country codes
   • Taiwan: 886
   • Russia, Kazakhstan: 7
   • Uzbekistan: 998 All are listed as regions that require opt‑in for MFA telephony verification.
2. Use an alternative MFA method to unblock users
   • Configure at least one non‑telecom‑based method (for example, Microsoft Authenticator app, hardware token, etc.), as recommended for tenants where telephony may be restricted or throttled.
3. Request telephony opt‑in for those regions (tenant‑level action)
   • An administrator must open a support request with Microsoft to enable SMS/voice MFA for each of these region codes for the tenant.
   • If users previously received SMS/voice in these countries but it stopped, throttling may be in effect; retry later or use an alternative method. If all users in the tenant are affected for a listed country, it likely means the tenant is not enabled for telecom authentication in that region and a support ticket is required.
4. After Microsoft enables telephony for those regions
   • Have users retry adding the phone numbers with the correct country code and number format.
   • If errors persist, provide Microsoft Support with the correlation ID and timestamp from the error screen for deeper investigation.

References:

• Overview
• Configure Microsoft Entra multifactor authentication settings
• Localization string IDs